1. Field of the Invention
The present invention generally relates to electronic signal coupling and, more particularly, to a coupling device. The coupling device may be used to couple, for example, coaxial cables, tap blocks, and so forth.
2. Background of the Invention
Coaxial cable is in widespread use for distributing wide band radio frequency information, such as television and radio signals. The cable television/radio industry, which relies almost exclusively on coaxial cable, is one of the most rapidly expanding segments of the United States' economy. It is anticipated that in the very near future the amount and type of information available via coaxial cable networks will be greatly expanded beyond traditional television and radio signals. By the early part of the twenty-first century, coaxial cable networks may be the principal vehicle by which consumers obtain their daily news, access library information, do their shopping, pay their bills, and otherwise interact with much of the outside world. Maintaining and controlling the integrity of the coaxial cable distribution networks that will carry such a large amount and such a wide variety of consumer information and services is a major challenge for the cable network industry.
FIG. 1 is a diagram illustrating a coaxial cable to which the present invention may be applied, according to an illustrative embodiment of the present invention. Coaxial cable typically includes a pair of conductors, a central axial conductor 12 and an outer conductor 15 that is disposed concentrically around the central conductor 12. A low-loss, high dielectric insulation material 13, such as plastic foam, is used to separate the two conductors. An outer insulating jacket 10 is often provided over the concentric conductor 15 to provide electrical insulation and physical protection to the cable. The concentric conductor 15 may be a single continuous element or, more commonly, it is a composite of several layered elements of conductive foil, wire braid or similar material.
For ease of initial installation and for flexibility with respect to subsequent modifications, coaxial cable networks comprise lengths of cable connected to one another by some sort of connection equipment. In most coaxial cable networks, such connection equipment takes the form of a male/female connection system wherein the male member is provided by a connection jack and the female member is provided by a threaded or friction-fit coupler dimensioned to attach over the jack. A standard connection jack comprises a cylindrical, externally threaded body. The outwardly projecting end of the jack is covered by a planar member that has a central aperture. Behind the aperture, within the confines of the body of the jack, is disposed an internal conductor which is shielded from the body. The body is electrically connected to one of the coaxial cable circuits and the inner conductor is connected to the other coaxial cable circuit.
The female member in the typical male/female connection system commonly comprises a jack connection moiety that is adapted to attach to the cable connection jack. The female member also comprises a cable connection moiety which physically attaches to the terminus of a coaxial cable in such a way that the cable connection moiety is in electrical contact with the concentric conductor of the coaxial cable. The cable connection moiety is adapted to allow the terminus of the central conductor to project through the center of the female member without contacting the female member, so that, when the jack moiety is attached to the outside of the conductor jack body, the central conductor terminus protrudes into the connection jack central aperture (without contacting the jack connection moiety of the female member or the conductor jack body) and is placed into electrical contact with the internal conductor of the connection jack.
Coaxial cable networks are traditionally distributed to individual residences using existing telephone company poles and underground conduits. A coaxial cable “trunk” is run through a neighborhood in parallel with telephone and electrical lines, and each residence to be serviced by the cable network is connected into (“tapped into”) the trunk line. The interface between the trunk line tap and the cable line running to an individual residence (the “drop line”) is traditionally called a “tap block”. A tap block traditionally is a small metal box having a flat face plate called a “tap plate”. Projecting outwardly from the tap plate are several coaxial cable connection jacks. Each cable service-subscribing residence in the immediate vicinity of the tap block is connected to one of the connection jacks on the tap plate.
Typically, all of the services provided by the cable network company are available at the tap face connection jacks. If a residence chooses not to pay for certain special cable network services (such as the HBO™ television network and the Pay-Per-View™ television network), a “signal trap”’ is interposed between the tap face connection jack and the drop line for that individual residence. A signal trap is a small electrical device having an input connector jack and an output connector jack. The signal trap is electrically configured so as to filter out or scramble the signal of a non-subscribed-to cable service.
From the tap block, a drop line is run to each individual residence and is connected to individual “receivers” (i.e., televisions or radios). Where more than one receiver is used by the residence, the drop line will terminate at a “signal splitter” having one input connection jack and two or more output connection jacks. It is common practice for many coaxial cable networks to charge an additional subscriber fee for the use of signal splitters to connect up additional receiving devices.
The problem with the use of such typical coaxial cable connection equipment is that such equipment is easy to connect, disconnect and reconnect. It is unfortunately easy for a dishonest consumer to be able to surreptitiously tap into a coaxial cable network. It is also far too easy for a dishonest consumer to reconfigure his existing coaxial cable connection system to surreptitiously connect up the cable network to additional receiving devices and to reconfigure his cable network to eliminate signal traps.
In addition to the vulnerability of typical coaxial cable connection equipment to physical tampering, typical coaxial cable network connection equipment is also vulnerable to corrosive and/or otherwise degrading conditions within the atmosphere, such as moisture, dust, and smog.
There have been many attempts to make connection equipment for coaxial cable systems more tamper resistant and more resistant to degradation from ambient- conditions. However, none of these attempts has been wholly satisfactory. Either the prior attempts relied upon connection equipment that was insufficiently resistant to tampering and/or degradation from ambient conditions or the prior attempts relied upon connection equipment which was excessively expensive to manufacture and/or awkward, complex and expensive to install in the field. Also, many prior attempts relied on connection equipment that could not be retrofit onto existing coaxial cable connection jacks.
Accordingly, there is a need for a coaxial cable coupling device that provides increased tamper resistance. There is also a need for a coaxial cable coupling device that provides increased resistance to degradation from ambient conditions. There is a still further need for a coaxial cable coupling device that, while providing adequate resistance to tampering and ambient condition degradation, is inexpensive to manufacture and is easy and inexpensive to install. Finally, there is a need for a coaxial cable coupling device that, while providing adequate resistance to tampering and ambient condition degradation, can be retrofit into existing coaxial cable network systems.